The invention relates to a device for recording an information signal on a magnetic record carder, which device comprises
an input terminal for receiving the information signal, PA1 a recording amplifier having an input coupled to the input terminal and having an output coupled to an input of a magnetic head, which recording amplifier is adapted to drive a magnetic head with a write current of given amplitude, and PA1 compensation means for controlling the amplitude of the write current in dependence upon temperature variations which occur during recording, which compensation means include temperature detection means.
Such a device is known from Japanese Kokai 60-143.404.
The compensation means in the known device comprises a temperature detector arranged close to the magnetic head. The temperature detector detects the temperature in the vicinity of the magnetic head and generates a control signal whose magnitude is a measure of this temperature. The compensation means subsequently controls the write current amplitude in dependence upon the control signal so as to obtain a constant magnetisation level in the record carrier at varying temperature.
For a given write current amplitude the recording depth of the information signal in the record carrier during recording appears to be dependent on the temperature of the record carrier. A varying temperature consequently results in varying recording depths. A higher temperature generally leads to a larger recording depth, cf. Finn Jorgensen: "The complete handbook of magnetic recording", 3rd. edition, pp. 296/6.
Preferably, the recording level of a recording should be as constant as possible and have a given value. This is of particular importance for apparatuses which do not have an erase head and which make a new recording by overwriting the old recording. If the recording level of the old recording in the record carrier is not constant problems may arise in the sense that sometimes the old recording cannot be overwritten satisfactorily. This problem is of particular importance for the compatibility of record carriers if a record carrier on which an old recording has been made is to be overwritten by means of another recording device not having an erase head. This means that the afore-mentioned requirement of a recording depth which is as constant as possible applies both to devices with an erase head and devices without an erase head.
If this requirement is not met and a new recording is made over an old recording in devices without an erase head this new recording cannot be read satisfactorily during subsequent reproduction. If during recording the write current amplitude is now corrected for these temperature variations the desired recording depth can be obtained during the entire recording, with an adequate overwriting attenuation, so that a satisfactory read quality of the newly recorded information is attainable. In practice, the constancy of the recording depth obtained during a recording appears to be unsatisfactory in some cases.